The present invention relates to a tip rod in which a super-elastic alloy is used. Accordingly, the rod is applicable for a fishing rod, especially for “a fishing rod used in raft fishing” for catching black porgy and etc, and for a fishing rod for catching filefish and etc.
A fishing rod to be used in catching black porgy etc., on a raft is made short in length and light in weight. It is, for example, from 1.3 to 2.1 meters in entire length. It is also made particularly slender in the rod tip part so as to respond delicately. Tip rods to be used in raft fishing are manufactured on the premise that they are bent substantially. Patent document 1 listed below has disclosed a fishing rod provided with a layer of a fiber-reinforced resin made with a low-elastic material or a high elongation percentage material adjacent to a core material of a super-elastic alloy and also provided with a layer of a high-elastic and low-elongation percentage material outside said layer. Also disclosed is a fishing rod in which the elongation percentage is made approximate between a layer of a fiber-reinforced resin made with a low-elastic material or a high elongation material and a core material, thereby preventing boundary separation and making it possible to provide a substantial deflection for a long time.
However, super-elastic alloys are 3 to 8% in elongation, and glass fibers, a low-elastic material and also a high elongation percentage material, are 3.5 to 4% in elongation, thus making it difficult to approximate the elongation percentage. Even if the elongation percentage of the core material is made approximate to that of the adjacent layer, there is a difference in elongation between the adjacent layer and the outside layer, namely, a layer of high-elastic material (a layer of low-elongation percentage material). A tubular member tends to give an oval shape when the transverse section is deformed on the substantial bend of the rod, whereas a solid material will be difficult in giving an oval shape. It is, therefore, necessary to prevent boundary separation which may occur due to a difference in deformation characteristics between a core material and an outer body layer on the substantial bend, rather than approximation of the elongation percentage.
When a prepreg sheet or a tightening tape is made greater in tensile force for preventing inclusion of bubbles in manufacturing a particularly slender fishing rod such as a tip rod, the force may deflect fishing rod materials thus resulting in a problem of bent fishing rods. Further even if the deflection is not observed before the burning, deflection may occur due to internal stress during heating and burning. Deflected fishing rods are defective and result in a lower yield.
Further, the following patent document 2 has disclosed the structure of a fishing rod which is joined by screwing a solid tip rod made with a fiber-reinforced resin into a tubular rod body with the same material.
However, it is also possible as the structure of a fishing rod to manufacture only a tip part region by using a super-elastic alloy, to which a tubular body made of a fiber-reinforced resin is subsequently joined, thereby giving an entire fishing rod, in addition to the structure of a fishing rod, in which an entire length is made with a super-elastic alloy. In this connection, where a fiber-reinforced resin part is directly provided with screws as disclosed in the patent document 2, there is a problem that screw threads are fragile. Further, particularly in a case where a slender cylindrical fishing rod body is provided with screws, stress will concentrate on the part of screws, thus posing another problem. Although not disclosed in the patent document 2, there is a necessity for forming a step part in a tapered shape, with consideration given to prevention of the concentration of stress. Where an end part of the cylindrical fishing rod body is made a slanted condition, for example, reaming is provided. In this instance, a slender cylindrical fishing rod body made with a fiber-reinforced resin will easily develop cracks by processing pressure. Therefore, it is not preferable to give a direct treatment to a member made of a fiber-reinforced resin, in view of the manufacturing processes.
Patent document 1: Japanese Published Unexamined Patent Application No. 2001-37378
Patent document 2: Japanese Published Unexamined Patent Application No. 2002-233274